2x converter for 300d?

wrote:

In message ,
"Roger N. Clark (change username to rnclark)"
wrote:


Here are some examples that show the quality of this
setup:

http://clarkvision.com/imagedetail/r...lens-sharpness


Did you realize when you did these tests that the 100-400 is actually
only about 350mm at the long end? I think you were too far for your
100-400mm shots.

350mm is not suported by the image size. The size says it is
right on at 400. The short end, however, looks smaller than
would be with 100mm, so it is really less than 100mm at the
short end.

Roger

wrote:

In message ,
"Bart van der Wolf" wrote:


That is, for me anyway, the major reason for using a TC.
Magnifying a smaller projected image will also magnify the
size/visibility of sensor artifacts (grain/noise and resolution
limits). It's a trade-off with magnifying the lens aberrations by
using a TC.


Of course, none of this is happening in a vacuum, so going the TC route
for a borderline lens that may give better results with a TC than with
software zoom will often require compromising apertures (most of these
lenses are really bad wide open, even without a TC) and/or shutter
speeds, and/or ISO.

So, let's say you want to shoot at ISO 400, and you have the 10D or
300D, and a 2x Kenko Pro TC, and a Canon 75-300 zoom. The lens itself
needs to be stopped down to about f9 or 10 in Av or M mode before it
starts getting sharp at 300mm. That's f18 or f20 with the 2x converter.
Under hazy sunlight, that would require a shutter speed of about 1/80 or
1/100, far too long to hand-hold. Only the IS version of the lens would
be hand-holdable for this.

So, I agree that a TC that gives a soft mage combined with a borderline
lens may look better than software zoom of the lens by itself, it is
indeed quite rare that all of the factors that combine for a sharp image
will occur for many possible shots. It is more often an over-sampled
soft image, and/or with less DOF than desired, or motion blur. That's
not to say that some blurry images aren't interesting, but people should
know what they're getting into when they get a TC, especially with slow
and optically mediocre lenses.

I agree.

Roger

In message ,
"Roger N. Clark (change username to rnclark)"
wrote:

350mm is not suported by the image size. The size says it is
right on at 400. The short end, however, looks smaller than
would be with 100mm, so it is really less than 100mm at the
short end.

My 100-400 has only a 17% narrower FOV than my 300 f4L. Either my
100-400 has a different FOV, or my 300 is actually ~342mm.
--


John P Sheehy